<template>
  <div>
    <div style="font-size: 18px; margin-top: 5%; margin-bottom: 5%">
      请扫描屏柜二维码
    </div>
    <div class="camera_outer" style="margin-top: 5%">
      <!-- 播放流媒体 -->
      <video
        id="videoCamera"
        :width="videoWidth"
        :height="videoHeight"
        autoplay
        style="
          border: 2px solid;
          border-color: #d3d3d3;
          border-radius: 4px;
          box-shadow: inset 0 2px 12px 0 rgba(0, 0, 0, 0.1);
        "
      ></video>
      <!-- 用于对流媒体进行截图 -->
      <canvas
        style="display: none"
        id="canvasCamera"
        :width="videoWidth"
        :height="videoHeight"
      ></canvas>
      <div
        v-if="imgSrc"
        class="img_bg_camera"
        v-loading="loading"
        element-loading-spinner="none"
        :element-loading-text="scanResultText"
        element-loading-background="rgba(0, 0, 0, 0.8)"
      >
        <img :src="imgSrc" alt="" class="tx_img" />
      </div>
    </div>
    <div style="position: absolute; left: 0; right: 0">
      <el-button type="info" style="margin-right: 10%" :disabled="true"
        >上一步</el-button
      >
      <div class="myButton" style="display: inline-block">
        <el-button
          style="margin-top: 10%"
          type="info"
          circle
          @click="start()"
          :icon="buttonIcon"
        ></el-button>
      </div>
      <el-button
        type="info"
        style="margin-left: 10%"
        @click="next()"
        :disabled="!hasResult"
        >下一步</el-button
      >
    </div>
  </div>
</template>

<script>
export default {
  name: "qrCode",
  data() {
    return {
      videoWidth: 300,
      videoHeight: 300,
      imgSrc: "",
      thisCancas: null,
      thisContext: null,
      thisVideo: null,
      buttonIcon: "el-icon-full-screen",
      loading: false,
      hasResult: false,
      scanResultText: null,
      number: null,
    };
  },
  mounted() {},
  methods: {
    start() {
      if (!this.hasResult) {
        this.getCompetence();
        this.scan();
      } else {
        this.imgSrc = null;
        this.buttonIcon = "el-icon-full-screen";
        this.loading = false;
        this.hasResult = false;
        this.number = null;
        this.scan();
      }
    },
    // 调用权限（打开摄像头功能）
    getCompetence() {
      var _this = this;
      this.thisCancas = document.getElementById("canvasCamera");
      this.thisContext = this.thisCancas.getContext("2d");
      this.thisVideo = document.getElementById("videoCamera");
      // 旧版本浏览器可能根本不支持mediaDevices，我们首先设置一个空对象
      if (navigator.mediaDevices === undefined) {
        navigator.mediaDevices = {};
      }
      // 一些浏览器实现了部分mediaDevices，我们不能只分配一个对象
      // 使用getUserMedia，因为它会覆盖现有的属性。
      // 这里，如果缺少getUserMedia属性，就添加它。
      if (navigator.mediaDevices.getUserMedia === undefined) {
        navigator.mediaDevices.getUserMedia = function (constraints) {
          // 首先获取现存的getUserMedia(如果存在)
          var getUserMedia =
            navigator.webkitGetUserMedia ||
            navigator.mozGetUserMedia ||
            navigator.getUserMedia;
          // 有些浏览器不支持，会返回错误信息
          // 保持接口一致
          if (!getUserMedia) {
            return Promise.reject(
              new Error("getUserMedia is not implemented in this browser")
            );
          }
          // 否则，使用Promise将调用包装到旧的navigator.getUserMedia
          return new Promise(function (resolve, reject) {
            getUserMedia.call(navigator, constraints, resolve, reject);
          });
        };
      }
      var constraints = {
        audio: false,
        video: {
          width: this.videoWidth,
          height: this.videoHeight,
          transform: "scaleX(-1)",
        },
      };
      navigator.mediaDevices
        .getUserMedia(constraints)
        .then(function (stream) {
          // 旧的浏览器可能没有srcObject
          if ("srcObject" in _this.thisVideo) {
            _this.thisVideo.srcObject = stream;
          } else {
            // 避免在新的浏览器中使用它，因为它正在被弃用。
            _this.thisVideo.src = window.URL.createObjectURL(stream);
          }
          _this.thisVideo.onloadedmetadata = function (e) {
            _this.thisVideo.play();
          };
        })
        .catch((err) => {
          console.log(err);
        });
    },
    scan() {
      let _this = this;

      let scheduler = setInterval(function () {
        let code = _this.decodeQR();
        if (code !== null) {
          clearInterval(scheduler);
          _this.buttonIcon = "el-icon-refresh-left";
          _this.loading = true;
          _this.scanResultText = "当前屏柜号：" + code.data;
          _this.hasResult = true;
          _this.number = code.data;
        }
      }, 200);
    },
    //  绘制图片（拍照功能）
    decodeQR() {
      var _this = this;

      if (_this.thisContext === null) return;

      // 点击，canvas画图
      _this.thisContext.drawImage(
        _this.thisVideo,
        0,
        0,
        _this.videoWidth,
        _this.videoHeight
      );
      // 获取图片base64链接
      var image = this.thisCancas.toDataURL("image/png");
      _this.imgSrc = image;

      var frame = _this.thisContext.getImageData(
        0,
        0,
        _this.videoWidth,
        _this.videoHeight
      );
      var code = this.$jsQR(frame.data, _this.videoWidth, _this.videoHeight);

      return code;
    },
    // base64转文件
    dataURLtoFile(dataurl, filename) {
      var arr = dataurl.split(",");
      var mime = arr[0].match(/:(.*?);/)[1];
      var bstr = atob(arr[1]);
      var n = bstr.length;
      var u8arr = new Uint8Array(n);
      while (n--) {
        u8arr[n] = bstr.charCodeAt(n);
      }
      return new File([u8arr], filename, { type: mime });
    },
    // 关闭摄像头
    stopNavigator() {
      this.thisVideo.srcObject.getTracks()[0].stop();
    },
    next() {
      var _this = this;
      this.$store.dispatch("setNumber", _this.number);
      this.$emit("nextStep");
    },
  },
};
</script>

<style lang="scss" scoped>
.camera_outer {
  position: relative;
  overflow: hidden;
  //background: url("../../assets/img/user_0608_04.png") no-repeat center;
  background-size: 100%;
  video,
  canvas,
  .tx_img {
    -moz-transform: scaleX(-1);
    -webkit-transform: scaleX(-1);
    -o-transform: scaleX(-1);
    transform: scaleX(-1);
  }
  .btn_camera {
    position: absolute;
    bottom: 4px;
    left: 0;
    right: 0;
    height: 50px;
    background-color: rgba(0, 0, 0, 0.3);
    line-height: 50px;
    text-align: center;
    color: #ffffff;
  }
  .bg_r_img {
    position: absolute;
    bottom: 0;
    left: 0;
    right: 0;
    top: 0;
  }
  .img_bg_camera {
    position: absolute;
    bottom: 0;
    left: 0;
    right: 0;
    top: 0;
    img {
      width: 300;
      height: 300;
    }
    .img_btn_camera {
      position: absolute;
      bottom: 0;
      left: 0;
      right: 0;
      height: 50px;
      line-height: 50px;
      text-align: center;
      background-color: rgba(0, 0, 0, 0.3);
      color: #ffffff;
      .loding_img {
        width: 50px;
        height: 50px;
      }
    }
  }
}
</style>

<style>
.myButton .el-button--info:focus,
.el-button--info:hover {
  background: #a6a9ad;
  border-color: #a6a9ad;
  color: #fff;
}
.myButton .el-button.is-circle {
  border-radius: 50%;
  padding: 12px;
}
.myButton .el-button:focus,
.el-button:hover {
  color: #409eff;
  border-color: #c6e2ff;
  background-color: #ecf5ff;
}
.myButton .myButton .el-button--info {
  color: #fff;
  background-color: #909399;
  border-color: #909399;
}
.myButton .el-button {
  display: inline-block;
  line-height: 1;
  white-space: nowrap;
  cursor: pointer;
  background: #fff;
  border: 1px solid #dcdfe6;
  color: #606266;
  -webkit-appearance: none;
  text-align: center;
  -webkit-box-sizing: border-box;
  box-sizing: border-box;
  outline: 0;
  margin: 0;
  -webkit-transition: 0.1s;
  transition: 0.1s;
  font-weight: 500;
  padding: 12px 20px;
  font-size: 25px;
  border-radius: 4px;
}
.myButton .el-button,
.el-checkbox {
  -webkit-user-select: none;
  -moz-user-select: none;
  -ms-user-select: none;
}
</style>